That appears to be 5kW for one hour. Amazing! Take out inefficiencies, and you probably have 5kW for 1/2 hour. 90% generator eff, 90% transmission efficiency, 90% extraction efficiency, 10% power loss from friction - so 40% loss right there in rough estimate.

But, can we do a 1000kg wheel with mass-on-rim at 1 meter? That is huge. And how to drive it? With continuously variable transmission?